— Recently, Hwang et al. introduced a knapsack type public-key cryptosystem. They proposed a new algorithm called permutation combination algorithm. By exploiting this algorithm, they attempt to increase the density of knapsack to avoid the low-density attack. We show that this cryptosystem is not secure, as it based on basic Merkel-Hellman knapsack cryptosystem and because of the superincreasi...

In this paper, we cryptanalyze two knapsack cryptosystems. The first one is proposed by Hwang et al [4], which is based on a new permutation algorithm named Permutation Combination Algorithm. We show that this permutation algorithm is useless to the security of the cryptosystem. Because of the special super increasing structure, we can break this cryptosystem use the method provided by Shamir a...

WTLS (Wireless Transport Layer Security) is an important standard protocol for secure wireless access to Internet services. WTLS employs public-key cryptosystems during the handshake between mobile client and WAP gateway (server). Several cryptosystems at different key strengths can be used in WTLS. The trade-off is security versus processing and transmission time. In this paper, an analytical ...

This paper presents a survey of key evolving cryptosystems in the public key setting, focusing on two main approaches: ‘forward security’ and ‘intrusion resilience’. The essential feature of this design strategy is that the secret key changes over time, while the corresponding public key remains unchanged. Key evolving cryptosystems can limit the damage caused by an attacker who occasionally le...

In the last decade, a number of public key cryptosystems based on combinatorial group theoretic problems in braid groups have been proposed. We survey these cryptosystems and some known attacks on them. This survey includes: Basic facts on braid groups and on the Garside normal form of its elements, some known algorithms for solving the word problem in the braid group, the major public-key cryp...

An important problem of modern cryptography concerns secret public-key computations in algebraic structures. We construct homomorphic cryptosystems being (secret) epimorphisms f : G → H, where G,H are (publically known) groups and H is finite. A letter of a message to be encrypted is an element h ∈ H, while its encryption g ∈ G is such that f(g) = h. A homomorphic cryptosystem allows one to per...

We give an overview of the most important public-key cryptosystems and discuss the difficult task of evaluating the merit of such systems.

A b s t r a c t The f i r s t p a r t of t h i s paper g i v e s r e s u l t s about promise problems. A "promise problem" i s a formulation of a p a r t i a l d e c i s i o n problem t h a t i s u s e f u l f o r d e s c r i b i n g cracking problems f o r public-key cryptosystems (PKCS). We prove t h a t every NP-hard promise problem i s uniformly NP-hard, and w e show t h a t a number of r e...